Transmission troubles

I have had it with the dealer! I have a 2007 VW Jetta, Wolfsberg edition- automatic transmission. I have brought my car in for the 3rd time with the same problem and they don’t have a “code” so they don’t know what to do. After driving at highway speeds, even just 50 for 30 minutes or more and the decelerate, on an off ramp for example, occasionally it seems the gears between 4th and 3rd don’t connect right away and there is a sensation of the engine tripping over itself. At first it was so suttle that I wasn’t sure it actually happened, now it is becoming a significant jerk. Unfortunitely, this isn’t consistant so the dealer can’t replicate it and the computer on board isn’t providing a code for the problem. Any suggestions?

First of all, do you have an extended power-train warranty? This would include your transmission as well as your engine and all drive-train gearing and drive wheel components. It is possible the dealer is biding it’s time in making a “diagnosis” based on a known defect until your warranty expires.
There is no code for your problem that I am aware of. And it very unlikely that a cursory drive around the block is going to reproduce what you are experiencing after driving “just 50 or 30 minutes”. But certainly there is a problem with your drive train, and the problem probably has to do with your transmission. If the problem was strictly mechanical (your transmission is a hydraulic system), it would happen all of the time or more often than not.
But as automatic transmission failures go, your problem is not usual. Most often transmissions fail to shift from one gear to the next, while accelerating. You might want to search online to see if other Jetta owners have experienced this same problem.
If the problem cannot be solved, look up lemon laws. This is a fairly new car in any case. If the dealer cannot even resolve the issues with a car it should know better than anyone else, then the car is a lemon.
If you are covered by statute, you have the law on your side. Document everything you can including the car’s misbehaviors (have a friend record the symptoms on an i-phone or whatever) and if you receive no paperwork from the dealer, write down what you were told and when.
Lastly, contact the manufacturer and request information about your problem before anything else. It might be that they can help you out. They may provide evidence of a known defect.
Your dealer is not the manufacturer. It might be that the dealer you are going to is just ducking costs.

I’ll bet it’s a problem with the torque converter lockup.
Have the electrical connectors to the trans reseated and checked.
Have the trans fluid changed if it’s been in there over 30K miles.